Through the end of the year, reporters will look back at and follow up on stories and topics that resonated strongly with our readers in 2018, according to metrics on lohud.com. This story is part of that series.

It was the pop heard ‘round New York.

On Sept. 7, as workers prepared to open the eastbound span of the Mario M. Cuomo Bridge to traffic for the first time, someone heard a pin joint pop on its 62-year-old neighbor, the Tappan Zee Bridge.

The noise stirred enough concern among engineers that plans to open the new span were scuttled, just hours after Gov. Andrew Cuomo had led a celebration for a bridge named for his father by taking his mother Matilda for a spin in a vintage Packard that once belonged to Franklin Delano Roosevelt.

And now, as the old bridge looms adjacent to the new superstructure, officials are floating the idea of demolition via explosives to finish its take down.

Three months after Cuomo's political rivals attacked him for putting politics ahead of public safety, the key combatants in the skirmish on the Hudson have gone their separate ways. In November, Cuomo was elected to a third term after defeating Cynthia Nixon in the primary and Republican Marc Molinaro in the general election.

But the superstructure of the old bridge remains undisturbed, jutting out of the Hudson like some turn-of-the-century shipwreck.

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The remaining structure of the Tappan Zee Bridge photographed from Grandview-on-Hudson on Tuesday, December 4, 2018. (Photo11: John Meore/The Journal News)

And no one seems to know when – or how – it’s going to come down.

"There's clearly something wrong, and the public needs to know exactly what it is,” said William O’Reilly, Molinaro’s spokesman. “This isn't a blame game, it's a where-do-we-go-from-here issue. Let's make the facts public and decide what the most responsible course of action needs to be. The silence is deafening."

Tappan Zee Constructors, the consortium hired by the New York State Thruway Authority to build the $3.9 billion bridge and demolish the old one, says it's still working on a plan.

“In the interest of the safety of our workers and the travelling public, Tappan Zee Constructors is reviewing alternative means and methods to remove the old Tappan Zee Bridge’s east anchor span," spokeswoman Laura Ware said. "TZC is working with local, state, and federal agencies and various experts to determine the safest way to lower the span. At this time, the east anchor span conditions remain unchanged from Tappan Zee Constructors’ previous assessment.”

Blow it up?

One alternative being explored is the use of explosives.

In late November, Tappan Zee Constructors sent a proposal to the Federal Highway Administration (FHA) suggesting the explosives option. Such permission is necessary because the new plan differs from the original, which involved taking the bridge down piece by piece.

“The Federal Highway Administration is working with many interested parties to evaluate Tappan Zee Constructors’ demolition plans to ensure the safe removal of the bridge," FHA spokesman Doug Hecox said Friday.

Hecox said TZC is proposing such a plan because the old bridge is considered structurally unsound.

"Workers can't get on it to do the things they were planning to do," Hecox said. "The contractor is being forced to look at things a little bit differently and so that’s what we’re reviewing right now."

A decision could come as early next week. Hecox said before moving ahead, the FHA will solicit input from interested parties, including Riverkeeper and the National Marine Fisheries Service, which will have to decide if explosives will have an adverse impact on the Atlantic sturgeon, a protected species.

As historical moments go, the loud pop may never equal the significance of, say, the opening shot of the Revolutionary War or Bobby Thomson’s home run to snatch the 1951 National League pennant away from the Brooklyn Dodgers.

But for a few days in September, it sure sounded that way.

Nixon called for an investigation after the opening of the eastbound lanes was called off on Sept. 7.

“A ribbon cutting ceremony should not have been held if the bridge span was not yet safe,” Nixon declared.

Molinaro joined in. “It’s now clearer than ever the bridge was opened to meet Governor Cuomo’s political agenda,” Molinaro said.

A statement from Tappan Zee Constructors said the old bridge was damaged but stable. It did little to quell public fears.

“While there remains a possibility of the old bridge east span failing, in the event it does, it will fall within a safety zone that does not affect vessel traffic or the structural integrity of the new eastbound bridge,” the statement said.

The governor could barely contain his anger at the suggestion he would place the public’s safety at risk. He noted that Tappan Zee Constructors technically owned the old bridge.

"The bridge is ready to open," Cuomo said when a reporter questioned him about the political implications. "Unless you think we should keep (people stuck in traffic)."

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Governor Andrew Cuomo, his mother Matilda, Secretary Hillary Rodham Clinton and family pose for a photo after unveiling the plaque during the grand opening of the second span of the new Governor Mario M. Cuomo Bridge, Sept. 7, 2018. (Photo11: Mark Vergari/The Journal News)

The eastbound span opened to traffic on Sept. 11, with four lanes for drivers headed to the Westchester County side of the river.

Lots of Tappan Zee gone

Meanwhile, much of the old bridge has already been removed, a demolition that involved 300,000 tons of concrete, 47,000 tons of steel and 13,000 timber pilings.

Work to remove the remaining steel structure, which sits 160 feet away from the new bridge, was supposed to wrap up by the end of October. Work on the structure beneath the water was planned for next year.

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The remaining structure of the Tappan Zee Bridge, at right, photographed from Upper Grandview on Dec. 4.(Photo11: John Meore/The Journal News)

In the meantime, the Coast Guard continues to restrict barges, cargo ships, tankers and other vessels from passing under the new bridge near the old bridge. They’ve been diverted to a 300-foot channel on the western side, near the Rockland County shoreline.

The Coast Guard has yet to receive word on when things might change and referred questions about the timetable to the Thruway Authority, a spokesman said.

John Lipscomb, who patrols the Hudson River for Riverkeeper, said he hasn't been told what sort of methods are being considered for taking down the old bridge.

“We have reached out to the state to try and be part of that deliberation, so the interests of the Hudson can be considered,” Lipscomb said. “That’s our job. To speak for the river.”

But Lipscomb said he was heartened by the decision made in September to delay the opening of the eastbound span, which he took as an indication the state and its builder have the public’s safety in mind.

“Even though you look at the bridge and it’s sitting there, it doesn’t mean there isn’t an intense review of alternatives under way. As long as it’s there it’s a liability and when it’s gone it’s not. When the engineer notified the state of that risk on the day of the grand opening, that took some guts and integrity. That was not a day when your message was going to be popular at all. It gives me confidence they put safety before anything else.”